Improve error message for `E0659` if the source is not available

diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 2e4cb4ff7270d75cd451d9b0f3e3ef301667ec56..6a13627a56314f11cb9359ca9348ed8bafeae7a6 100644 (file)
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -1178,7 +1178,7 @@ fn lookup_import_candidates_from_module<FilterFn>(
 
     fn binding_description(&self, b: &NameBinding<'_>, ident: Ident, from_prelude: bool) -> String {
         let res = b.res();
-        if b.span.is_dummy() {
+        if b.span.is_dummy() || self.session.source_map().span_to_snippet(b.span).is_err() {
             // These already contain the "built-in" prefix or look bad with it.
             let add_built_in =
                 !matches!(b.res(), Res::NonMacroAttr(..) | Res::PrimTy(..) | Res::ToolMod);